Gratitude is a thankful appreciation for what an individual receives, whether tangible or intangible. With gratitude, we acknowledge – and often feel – a sense of wonder, thankfulness and appreciation for life. In the process, people usually recognise that the source of that goodness lies at least partially outside of themselves.

Most of us are taught basic gratitude as children as we learn to say thank you, show respect and help others. But in this busy world, I fear many of us have become expectant of certain things, feeling it’s our right to live our lives in a particular way and taking the ordinary things for granted.

In psychology research, gratitude is strongly and consistently associated with so many wonderful things. I’ve condensed the literature into seven key points:

Gratitude makes you new friends. Not only does saying “thank you” constitute good manners, but showing appreciation can open the door to new realationships. A 2014 study found that thanking a new acquaintance makes them more likely to seek out an ongoing relationship with you. So whether you thank a stranger for holding the door or send a thank-you note to that colleague who helped you with a project, acknowledging other people’s contributions can lead to new opportunities.

Gratitude improves your physical health and you will live longer. Turns out people who practice gratefulness experience fewer aches and pains and feel healthier than other people. These people are also more likely to take care of their health, exercise more often, more likely to attend check-ups and just more likely to live longer in general.

Gratitude makes you feel good. Gratitude improves psychological health. It reduces a multitude of toxic emotions, from envy and resentment to frustration and regret. Robert Emmons, a leading gratitude researcher, has conducted multiple studies on the link between gratitude and well-being. His research confirms that gratitude effectively increases happiness and reduces depression.

Gratitude makes you fight less. Gratitude enhances empathy and reduces aggression. Grateful people are more likely to behave in a prosocial manner, even when others behave less kindly, according to a 2012 study by the University of Kentucky. Study participants who ranked higher on gratitude scales were less likely to retaliate against others, even when given negative feedback. They experienced more sensitivity and empathy toward other people and a decreased desire to seek revenge.

Gratitude helps you sleep. Turns out the people who practice gratitude also sleep better. A 2011 study found that people who wrote in a gratitude journal - spending just 15 minutes jotting down a few grateful sentiments before bed – meant they slept better and longer than those who didn’t journal.

Gratitude makes you feel better about yourself. It improves self-esteem. A 2014 study found that gratitude increased athletes’ self-esteem, an essential component to optimal performance. Other studies have shown that gratitude reduces social comparisons. Rather than becoming resentful toward people who have more money or better jobs—a major factor in reduced self-esteem—grateful people are able to appreciate other people’s accomplishments.

Gratitude increases mental strength. For years, research has shown gratitude not only reduces stress, but it may also play a major role in overcoming trauma. A 2006 study found that Vietnam War veterans with higher levels of gratitude experienced lower rates of post-traumatic stress disorder and a 2003 revealed that gratitude was a major contributor to resilience following the terrorist attacks on September 11. Recognising all that we have to be thankful for —even during the worst times—fosters resilience.

There’s a lot of people around who might describe themselves as ‘grateful’. And sure it might be a personality trait. But it’s also a mental muscle that can always be strengthened for optimal performance.

We feel and express gratitude in multiple ways. We can apply it to the past (retrieving positive memories and being thankful for elements of childhood or past blessings), the present (not taking good fortune for granted as it comes), and the future (maintaining a hopeful and optimistic attitude). Regardless of the inherent or current level of our gratitude, it's a quality that we can successfully cultivate further.

So, the challenge for our Mental Muscle Marathon is to partake in at least one purposeful act of gratitude.

Here’s some fresh ideas to cultivate gratitude:

Write a thank-you note to someone. Express your enjoyment and appreciation of that person's impact on your life. Send it, or better yet, deliver and read it in person if possible.

Thank someone mentally. No time to write? It may help just to think about someone who has done something nice for you, and mentally thank the individual.

Start a gratitude journal. Make it a habit to write down or share with a loved one thoughts about the gifts you've received each day.

Count your blessings. Pick a time today to sit down and write about your blessings — reflecting on what went right or what you are grateful for. Sometimes it helps to pick a number — such as three to five things — that you will identify. As you write, or think, be specific and think about the sensations you felt when something good happened to you.

Meditate. Mindfulness meditation involves focusing on the present moment without judgment. Although people often focus on a word or phrase (such as "peace"), it is also possible to focus on what you're grateful for (the warmth of the sun, a pleasant sound, etc.).

Make a gratitude date. Sit down with a partner. Or friend or family member. And discuss all the things you are thankful for. Together.